Control method and device for the excavation depth of an excavator

ABSTRACT

A control device for excavation depth (P) of an excavator ( 2 ), having a first arm ( 3 ), a second arm ( 4 ) and a bucket ( 5 ) mutually constrained, is provided with a first angular sensor ( 6 ) associated with first arm ( 3 ), a second angular sensor ( 7 ) associated with second arm ( 4 ), a central unit ( 8 ), to which are connected the first ( 6 ) and second ( 7 ) sensors and a display ( 9 ) connected to the central unit ( 8 ). The central unit ( 8 ) acquires main data of excavator ( 2 ) and initial values from first ( 6 ) and second ( 7 ) sensors, corresponding to angular dispositions of first arm ( 3 ) and second arm ( 4 ) respectively, on the basis of which the excavator determines a zero excavation quota (Q). The central unit ( 8 ) acquires continuous values from the sensors, corresponding to an excavation condition (S) to calculate the excavation depth (P) that is also visible on display ( 9 ).

BACKGROUND

The present invention relates to the technical field concerning construction and earth moving machines and in particular refers to a method and device for controlling the excavation depth of an excavator.

EP 1 186 720 describes a device for monitoring the excavation depth associated with an excavator, equipped with a control unit and with angular sensors capable of sending proportional values of angular variations of mutually articulated arms relative to a connected excavator bucket.

A laser sensor, external to the monitoring device, detects and sends to the control unit a value corresponding to the so-called “zero excavation level”.

The control unit compares the detected values corresponding to angular variations of the arms and bucket with the value of zero level to determine the excavation quota to which the bucket is positioned.

This excavation quota is displayed on a viewer so that an operator can make a profitable use thereof.

The main disadvantage of the known control device is that the laser device is separated from the monitoring device itself, is bulky and difficult to use, as well as requiring the use of a dedicated operator.

SUMMARY

The main object of the present invention is to propose a method and a device for controlling the excavation depth of an excavator fit for independently detecting the zero excavation level, that is, the starting level, and consequently detecting the instantaneous depth of the performed excavation.

Another purpose is to propose a device which is easy to install, with reduced sensor cost and allowing the use of display and processing means of common use and of reduced overall dimensions.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristics of the invention are highlighted below with particular reference to the attached drawings in which:

FIG. 1 is a schematic view of the depth monitoring device of an excavator bucket;

FIG. 2 show the device of FIG. 1 in an initial condition for determining the zero excavation level and are shown in broken lines, in which parts are removed to better highlight others, the bucket position at an intermediate and final conditions determining this zero level;

FIG. 3 shows the device of FIG. 1 in an excavation condition.

DETAILED DESCRIPTION

With reference to FIGS. 1-3, numeral 1 is the device of the present invention, which is associated with an excavator 2 to automatically determine a selected or desired depth of an excavation, e.g., selected by an operator of the excavator.

The excavator 2 essentially comprises the following elements directly related to the present invention:

-   -   a first arm 3 having a first length L1 and which is hinged, at         one end thereof, to the frame 15 of excavator 2, in a first         hinge 11 placed at a first distance D1 from ground on which a         moving set 16 slides and which is made of tracks or wheels of         the excavator itself;     -   a second arm 4 having a second length L2 and which is hinged, at         one end thereof, to the remaining end of first arm 3 in a second         hinge 12;     -   a bucket 5, designed to collect ground portions, hinged to the         remaining end of the second arm 4 by means of a third hinge 13         whose axis is placed at a second distance D2 from the excavation         edge 10 of bucket 5;     -   a first angular sensor 6 associated with the first arm 3;     -   a second angular sensor 7 associated with the second arm 4;     -   a central unit 8, to which the sensors are connected, first 6         and second 7;     -   a display 9 linked to central unit 8, for example of touch type         for displaying and entering data.

The arms, first 3 and second 4, and bucket 5 are moved around hinges, first 11, second 12 and third 13 by means of respective hydraulic pistons 17. From the geometry it is known as, starting from the knowledge of the dimensional parameters of bucket 5, arms 3, 4 and the zenith angle of these latter, it is possible to calculate instantaneously the position and orientation of bucket 5. This problem is identified in the robotic field as a direct kinematic problem.

The joint angles are variable and dependent on the extension of hydraulic pistons 17 which actuate respective arms 3, 4. These angles are measured by the sensors, first 6 and second 7, for example of an inertial type IMU (Inertial Measurement Unit) or other type of absolute angular sensor or able to provide the azimuth height angle or its reciprocal.

These sensors, first 6 and second 7 represent a solution of maximum flexibility, as they provide the orientation of each sensor 6, 7 with respect to a terrestrial inertial reference system.

This is for positioning sensors 6, 7 at any point of arms 3, 4 and of bucket 5 and not necessarily at the rotation joint or hinge. This positioning avoids the placing of measuring instrument between two moving members, so greatly simplifying the installation, reliability and adaptability, allowing in fact the subsequent implementation and therefore the installation of control device 1 at any time during the excavator life.

The angular sensors, first 6 and second 7, are fixed to the excavator 2 by means of fixing means, for example brackets, clamps, or also with glue or detachable fixing means.

The sensors, first 6 and second 7, are powered directly by excavator 2 by means of dedicated wiring or they are self-powered.

In an excavator 2 having axial rotation of the frame 15 with respect to the moving set 16, an orientation sensor 18, fixed to the frame 15 (or also to the moving set 16), is connected to central unit 8 and is designed to measure the rotation angle between the moving set 16 and the frame 15 or supporting portion.

The value of this rotation angle is sent to the central unit 8 which processes and transmits this latter to display 9 to allow the operator to bring the bucket 5 back into the excavation position, for example after a lateral rotation for discharging the material removed from soil.

The device 1 therefore comprises the angular sensors, first 6 and second 7, the central unit 8 and the display 9 which are mutually connected and respectively detect, process and display data in order to first determine a zero excavation level Q, normally the ground level, and thus the achievement of an excavation depth P during an excavation condition S.

The operation of device 1 therefore provides that the central unit 8 acquires the main data of excavator 2 corresponding to first distance D1, first length L1, second length L2 and second distance D2. This data can be entered manually by user via the display 9 or by other computer support of USB (Universal Serial Bus) key type or via a Wi-Fi connection or via a Bluetooth connection.

Then the central unit 8 acquires initial values from the first sensor 6 and from the second sensor 7 which correspond to the angular arrangements of first arm 3 and second arm 4, for example with respect to the vertical, at least at an initial condition C1, an intermediate condition C2 and a final condition C3 in which respectively the bucket 5 is positioned on the ground and is then moved over the ground for a determined portion T of the latter and is finally stopped on the ground, still maintaining the third hinge 13 almost constantly at the second distance D2 from the ground. In other words, the operator, by sliding parallel to and resting on the ground the excavation edge 10 of bucket 5, allows the central unit 8 to activate the calibration and determination procedure of the zero excavation level Q from which it will compute the desired depth P of the excavation.

The central unit 8 interpolates the initial values in order to correlate them with the main data of the distances D1 and D2 and of the lengths L1 and L2 to determine the zero excavation level Q.

In an excavation condition S in which the operator operates the bucket 5 by means of the arms 3, 4, the sensors, first 6 and second 7, continuously send the angular values, corresponding to angular dispositions of first 3 and second 4 arms, to central unit 8. Then the central unit 8 can continuously integrate initial values and continuous values coming from the sensors, first 6 and second 7, with main data of excavator 2 until the central unit 8 detects that the bucket 5 has reached an excavation depth P equal to the predetermined one calculated from the zero excavation level Q.

At this point, the device 1 has reached the purpose of informing the excavator operator of reaching the desired excavation depth P.

Lastly, the central unit 8 sends, also continuously and not only upon reaching the depth P, to the display 9 the value of the excavation level Q, in particular the desired excavation depth P when it is reached.

It is to be understood that on the display 9, data, values and parameters that may be necessary for the excavator operator 2 can be displayed, even with continuity.

The angular sensors, first 6 and second 7, the orientation sensor 18, and the central unit 8 and/or the display 9 may communicate via wireless, preferably with Bluetooth wireless connections, WIFI wireless connections or similar systems, but may instead communicate via wired connections or in a selected combination of wireless and wired connections.

The display 9 may be a mobile device of the tablet, smartphone and similar type, provided with a wireless connection, preferably via Bluetooth, WIFI or similar systems, to communicate with the central unit 8 but may be a fixed type.

The display 9 and the central unit 8 may be integrated into a single mobile device such as tablets, smartphones, or the like.

A variant of the device 1 provides that in the first arm 3 or in the second arm 4 or both, a telescopic extension 19 is inserted, illustrated for example by means of broken line in FIG. 1 on second arm 4, to which is associated a length sensor 14 connected to central unit 8 for sending the elongation value of the telescopic portion 19 in order to correctly determine the length, first L1 or second L2.

The invention also relates to a method for determining and controlling the excavation depth P of an excavator 2 equipped with the essential elements described above.

In particular, the method provides the basic steps to first acquire the main data of the excavator 2, then the initial values of the angular sensors, first 6 and second 7, in correspondence with the determination of the zero excavation level Q and finally the continuous values sensed from the angular sensors, first 6 and second 7, until reaching the desired excavation depth P.

The main steps of the method are therefore:

-   -   acquiring in the central unit 8 the main data of excavator 2         corresponding to the first distance D1, to the first length L1,         to the second length L2 and to the second distance D2;     -   positioning the excavation edge 10 of bucket 5 on the ground to         be excavated so that the third hinge 13 is at the second         distance D2 from ground;     -   acquiring in the central unit 8 the initial values from the         first sensor 6 and from the second angular sensor 7         corresponding to the angular arrangements of the first arm 3 and         the second arm 4 at least in correspondence with the initial         condition C1, the intermediate condition C2 and the final         condition C3 in which respectively the bucket 5 is positioned on         the ground, moved on the ground for a determined portion T and         stopped on the ground at the end of portion T, while maintaining         the third hinge 13 almost constantly at the second distance D2         from ground;     -   interpolating these initial values in the central unit 8 in         order to correlate them with the main data to determine the zero         excavation level Q;     -   acquiring in the central unit 8 the continuous values from the         angular sensors, first 6 and second 7, corresponding to the         angular dispositions of first arm 3 and of second arm 4         respectively, corresponding to the excavation condition S;     -   integrating the initial values and the continuous values with         the main data of the excavator 2 continuously into the central         unit 8 until a bucket depth value 5 is calculated equal to the         desired excavation depth P which is displayed on the display 9,         also together with the data and values computed by the central         unit 8.

The method involves transmitting the main data, the initial values and the continuous values between the angular sensors, first 6 and second 7, and the central unit 8 and/or between the latter and the display 9 via wireless, preferably with Bluetooth, WIFI or similar systems.

The main advantage of the invention is that of providing an excavation depth control method and device for an excavator able to independently detect the zero excavation depth and to detect the instantaneous excavation depth performed with respect to this zero level.

Another advantage is that of providing a device which is easy to install, with reduced cost of sensors and which allows to use of display and processing means of common use and with reduced overall dimensions. 

1) Control method for excavation depth (P) into ground by an excavator (2) equipped with at least: a moving set (16) which supports a frame (15) of the excavator (2); a first arm (3) having a first length (L1) rotatably connected to the frame (15) of the excavator (2) by means of a first hinge (11) placed at a first distance (D1) from the ground; a second arm (4) having a second length (L2) rotatably connected to one end to a remaining end of the first arm (3) by means of a second hinge (12); a bucket (5) rotatably connected to a remaining end of the second arm (4) by means of a third hinge (13) having an axis placed at a second distance (D2) from an excavation edge (10) of the bucket (5); a first angular sensor (6) associated with the first arm (3); a second angular sensor (7) associated with the second arm (4); a central unit (8), to which the first (6) and second (7) sensors are connected; a display (9) connected to the central unit (8); wherein said method comprises: acquiring into central unit (8) main data of the excavator (2) corresponding to the first distance (D1), the first length (L1), the second length (L2) and the second distance (D2); placing the excavation edge (10) of the bucket (5) on the ground to be excavated in such a way that the third hinge (13) is at the second distance (D2) from the ground; acquiring into the central unit (8) initial values from the first sensor (6) and from the second sensor (7) corresponding to angular dispositions of the first arm (3) and the second arm (4), at least at an initial condition (C1), an intermediate condition (C2) and a final condition (C3) in which respectively the bucket (5) is positioned on the ground, moved on the ground for a given tract (T) and stopped on the ground, still keeping the third hinge (13) constantly at substantially the second distance (D2) from the ground; interpolating at central unit (8) these initial values in order to correlate them with said main data to determine a zero excavation level (Q); acquiring continuous values in the central unit (8) from the first sensor (6) and the second sensor (7), corresponding to the angular dispositions of first (3) and second (4) arms respectively, corresponding to an excavation condition (S); integrating in the central unit (8) continuously the initial values and the continuous values with main data of excavator (2) and calculating achievement of the excavation depth (P) of the bucket (5) for visualization on the display (9). 2) The method according to claim 1, further comprising transmitting one or more of the main data, the initial values and the continuous values between the first (6) and second (7) sensors, and the central unit (8), the display (9), or both, via at least one wireless connection. 3) Control device for excavation depth (P) of an excavator (2) equipped with at least: a moving set (16) which supports a frame (15) of the excavator (2); a first arm (3), having a first length (L1), rotatably connected to the frame (15) by means of a first hinge (11) placed at a first distance (D1) from ground; a second arm (4) having a second length (L2) rotatably connected to one end to a remaining end of the first arm (3) by means of a second hinge (12); a bucket (5) rotatably connected to a remaining end of the second arm (4) by means of a third hinge (13) having an axis placed at a second distance (D2) from an excavation edge (10) of the bucket (5); a first angular sensor (6) associated with first arm (3); a second angular sensor (7) associated with second arm (4); a central unit (8), to which the first sensor (6) and the second sensor (7) are connected; a display (9) connected to the central unit (8); wherein the central unit (8) acquires main data of excavator (2) corresponding to the first distance (D1), the first length (L1), the second length (L2) and the second distance (D2); the central unit (8) acquires initial values from first sensor (6) and the second sensor (7) corresponding to angular dispositions of the first arm (3) and of the second arm (4), at least at an initial condition (C1), an intermediate condition (C2) and a final condition (C3) in which the bucket (5) is positioned on the ground, moved on the ground for a given tract (T) and stopped on the ground, always keeping the third hinge (13) constantly at substantially the second distance (D2) from the ground; the central unit (8) interpolates said initial values in order to correlate them with said main data to determine the zero excavation level (Q); the central unit (8) acquires continuous values from the first sensor (6) and the second sensor (7), corresponding to the angular dispositions of the first arm (3) and of the second arm (4) respectively, and corresponding to an excavation condition (S); the central unit (8) continuously integrates the initial values and the continuous values with the main excavator data (2) to calculate the selected excavation depth (P); the central unit (8) continuously sends to display (9) at least the value of the excavation level, in particular the selected excavation depth (P) when it is reached. 4) The control device according to claim 3, wherein the first sensor (6), the second sensor (7), and the central unit (8), the display (9), or both the central unit and the display communicate via wireless connections. 5) The control device according to claim 3, wherein the display (9) is a mobile device provided with a wireless connection. 6) The control device according to claim 5, wherein the display (9) and the central unit (8) are integrated in a single mobile device. 7) The control device according to claim 3, wherein the first sensor (6) and the second sensor (7) are provided with fixing means, of a removable or fixed type, to the respective first arm (3) and second arm (4). 8) The control device according to claim 3, wherein the first sensor (6) and the second sensor (7) are powered directly by the excavator (2) by means of dedicated wiring or are self-powered. 9) The control device according to claim 3, wherein at least one of the first arm (3) or the second arm (4) has at least one telescopic portion (19) to which a relative length sensor (14) is connected to the central unit (8) to send a signal having a magnitude indicative of a relative length of the telescopic portion (19) in order to correctly determine an extended first length (L1) or an extended second (L2) length. 10) The control device according to claim 3, wherein at least one orientation sensor (18) is connected to the frame (15) and is connected to the central unit (8) to which it sends the value of the angle of rotation between the frame (15) and the moving set (16). 